Introduction of Centrifugal Extraction Machine for Treatment of Oily Wastewater

Oil-water separation is mainly based on the difference in density of water and oil or chemical properties, using gravity sedimentation principle or other physical and chemical reactions to remove impurities or complete the separation of oil and water. The main methods are: gravity method, centrifugation method, electric desorption method, adsorption method, chemical method, evaporation method and air flotation method. Centrifugal extraction machines have obvious advantages for common water, heavy oil, diesel and petroleum water removal and salt removal.

Oil-water separation is a negative entropy process and energy must be added. At present, the most commonly used gravity sedimentation tanks and centrifugal equipment are separated by the difference in density between oil and water. As a new type of extraction and separation equipment, centrifugal extractor has the advantages of good material phase separation performance, large processing capacity, compact equipment, less auxiliary equipment, small plant area and other advantages, and has broad market prospects. For the gravity type oil-water separator, although it has been widely used in the market, there are many types, but the disadvantages are low processing capacity and large equipment footprint.

The centrifugal extractor utilizes different oil-water densities to generate different centrifugal forces for the high-speed rotating oil-water mixture, thereby separating the oil from the water. Since the centrifugal extractor can achieve very high rotational speeds, generating centrifugal forces of up to several hundred times the gravitational acceleration, the centrifugal extractor can completely remove the oil moisture and requires only a short residence time and a small equipment volume. In recent years, with the rapid development of domestic technology, the amplification of centrifugal extractor equipment has been verified and applied in many aspects, with very good market benefits.

Separation process

The oil water enters the drum under the action of the self-priming pump, and the compartment area formed by the sub-plate makes the oil and water quickly whirl synchronously with the rotating drum, thereby balancing the oil-water liquid with each other; under the action of centrifugal force, the water is more important During the flow, it gradually moves away from the center of the drum and leans against the wall of the drum; the oil with a small specific gravity gradually moves away from the wall of the drum toward the center. The separation zone is from the baffle to the light phase, ensuring sufficient time to form a liquid-liquid layer. Finally, the oil and water enter the collection chamber through the respective rafts, and are respectively taken out of the machine by the guide pipe to complete the two-phase separation process, and the single-stage extraction is completed.

The centrifugal extractor can be used for single-stage extraction or multi-stage treatment, and the multi-stage centrifugal extractor is connected in series to improve the separation effect, which is also called cascade extraction. The classification of the cascade extraction of different centrifugal extractors according to the flow pattern of the organic phase and the aqueous phase can be classified into the following three types.

1. Cross-flow extraction. The feed liquid is fed from the first stage, and the raffinate of the subsequent stages is subjected to cascade extraction in contact with the fresh organic phase.

2. Countercurrent extraction. The feed liquid and the organic phase flow into the centrifugal extractor from both ends, respectively, so that the aqueous phase containing the smaller extractable component is brought into contact with the organic phase, and the organic phase containing more extractable components is contacted with the feed liquid.

3. Fractionation extraction. The feed liquid containing the element to be separated is fed from a certain stage of the intermediate stage of the cascade centrifugal extractor, and the two ends are respectively flowed into the washing liquid and the organic phase which do not contain the substance to be separated. Such a cascade method is called fractional extraction.

Overview of features

(1) The separation effect of the two-phase material under the action of centrifugal force is obvious, and the treatment amount is large.

(2) The contact time of the two-phase material is short, and the input cost of the extractant is saved.

(3) High mass transfer efficiency, high level efficiency, convenient parking and no damage after parking.

(4) The equipment has a small footprint and low comprehensive investment cost.

(5) It has strong adaptability, high flexibility, can be operated intermittently, can be operated in a single operation, can be operated in continuous countercurrent, and there is no need to set up an interstage pump in the middle.

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